1. Field of the Invention
This invention relates to wave energy transmission apparatus. More specifically, the invention is a wave energy transmission apparatus designed to transmit optical wave energy from a high-temperature environment to a thermally-protected environment.
2. Description of the Related Art
Space vehicles encounter extreme elevated temperatures (>3000° F.) and dynamic pressures that have in some cases produced powdery char from thermally-induced, ablation-heat-shield charring during atmospheric re-entry. The resulting char can fly into radiometer measurement ports such as those installed for determining exterior re-entry heating conditions on Apollos IV and VI. The heat shield char filling the optical ports obstructs the spectral and thermal readings of the spectrometer or radiometer. Similar problems exist in wind tunnels, scramjet combustors, or laboratory applications when, for example, radiometer measurement ports are formed in a heat-shielding structure used to separate a high-temperature environment from a thermally-protected environment.
Additionally, transparent windows designed for high temperature environments typically have a crystalline structure. When exposed to re-entry or other high-temperature environments, differences in thermal expansion can develop along grain boundaries in crystalline windows and lead to window failure.